Structural Modifications of Headphone Front Chamber for Better Frequency Response: Experimental and Simulation Studies

Abstract

The supra-aural headphone concentrates the sound in the listener’s ears, so the loudspeaker sound is confined to the cavity between the pinna and the headphone casing. It is then directed toward the tympanic membrane through the ear-canal. The high-quality sound requirement of supra-aural headphone on one side and space limitation on the other prompted this research. Similarly, inherent sound leakages from headphone on one side and a need for loud sound on the other also impelled this research. This research proposes headphone design modifications for interaction between sound from the diaphragm’s rear and front side for improved frequency response. The changes attempt to stop the sound from the diaphragm’s rear side to leak to the external surrounding, and it is routed to interact with the sound from the front side of the diaphragm in two distinct ways due to the geometrical/structural modifications of the headphone front cover. Prototypes of three headphones (one traditional and two modified) have been modeled by computer-aided drafting software and fabricated by 3D printing. In parallel, equivalent circuits have been formed for the simulation as per the proposed headphone testing setup. The frequency response measurements of headphones have been done in an anechoic chamber using B&K HATS Type 4128. The simulated and measured responses of headphones demand modification of the equivalent circuit by adding the current-controlled voltage source. The optimum simulated performances of all three headphones with a modified equivalent circuit show an improved agreement with respective measured performances.